Passion flowers, or passiflora are tropical flowers from South America. To me it’s pretty impressive that most of them can deal with temperatures below freezing.
Truly cold hardy passion flower
The common blue passion flower, Passiflora Caerulea, is truly cold hardy, it will keep it’s leaves in winter when temperatures are above -12. Below that it drops its leaves but will spring back up in late spring to early summer. It does require some winter protection in the first year. I grew mine from seed, and let it overwinter in a pot the first year. The second winter I covered the root of the plant with a heap of dry leaves. You can also use gardening fabric, any type of mulch or burlap for this purpose. After that winter I didn’t bother giing it extra protection and it’s doing just fine.
Cold tolerant passion flowers (-5)
Most veraieties of passion flower fall under this category. They can handle a mild frost but anything more than that will cause them serious damage. The good news is that all passion flowers can be grown in pots!
- Passiflora Ligularis
- Passiflora Maliformis
- Passiflora Mollissima
- Passiflora Adenopoda
- Passiflora Cincinnata
I grow quite a few passion flowers in pots. Some get a head start in early spring in the greenhouse. Some overwinter in my unheated shed, where it’s quite dark. I wrap them in burlap and water them very little (maybe once a month, just so the soil doesn’t dry out. I put them outside in early march and watch the weather carefully. If it might freeze in the night they go back to the shed. In may all my passion flowers go outside untill the forecast predicts the first frost somewhere in november. Last year I planted the small (3L) pots in the garden. It made watering a lot easier in the summer and I was pleasantly surprised at how easy it was to dig them up for the winter.
This year I want to plant a mollisima in the ground next to a south facing wall and see if it does well with a bit of garden fabric in the winter.
Tender passion flowers (0)
Some passion flowers are tender plants. They can’s handle frost at all. For example Passiflora Nigradenia with white flowers. It’s one of the most fragrant passion flowers with edible fruit. So if you have a frost free greenhouse of a shed where winter temperatures don’t drop below freezing it’s worth considering to grow this plant. It will flower well in a pot of at least 2L- 5L. If you want fruit from it the pot should be big 5L or more.
When you grow passionflowers in pots: bigger pots is bigger plants. They do like quite a lot of feed and water in the growing season. I give mine a half strenght water soluable balanced fertilizer every week.